The invention generally relates to the field of power electronics. More particularly, the invention relates to power switching modules and power converters incorporating such modules. The invention also relates to a method for manufacturing a power switching module.
The desired energy transition toward renewable energy sources producing lower CO2 emissions places power electronics at the heart of current technological challenges. Energy conversion needs are present in almost all activity sectors, such as transportation, industry, lighting, heating, etc.
In the transportation field, the automotive industry, which is subject to very restrictive emissions standards regarding polluting discharges, is experiencing true technological change with vehicle electrification. Vehicle electrification, which is faced with the major weight, bulk and cost constraints that prevail in this mass production industry, requires technological advances in converters. Furthermore, the need for sufficient mileage autonomy for electric vehicles, or for hybrid vehicles in electric mode, is pushing hard toward increased operating voltage with the aim of reducing Joule losses related to the current, or toward manufacturing technologies that make it possible to increase low-voltage currents by parallelizing the components. The necessary technologies must make it possible to increase the compactness of the converters by increasing the cutoff frequency and reducing stray inductances.
Compromises must be struck in the converters in particular between the withstand voltage, the cutoff frequency, the maximum acceptable power density, the temperature, the reliability and the integration of new available materials.
Higher voltages oppose the compactness of the converters, since greater breakdown risks often require increased distances between components having different polarities. Higher switching frequencies are favorable to compactness but increase the switching losses and the power dissipated by the components and require a significant reduction of the stray inductive and capacitive elements. The maximum power density acceptable by the components limits the amplitude of the switched currents in order to keep the junction temperatures below critical values. High-performing cooling devices are necessary in order to maintain the heat balance of the converters and extract the dissipated energy as close as possible to the components. These high-performing cooling devices are essential for greater compactness and reliability.
The various constraints applicable to the converters have steered designers toward a modular architecture based on the combination of elementary power switching modules.
Two examples of elementary power switching modules are shown in FIGS. 1a and 1b. As shown in FIGS. 1a and 1 b, these elementary modules are formed by a transistor switching bridge, or half-bridge, arm. The bridge arm conventionally comprises a high side transistor and a low side transistor, and associated diodes. FIG. 1a shows a diagram of a first bridge arm BM made up of MOSFET transistors, MTHS and MTLS, and diodes MDHS and MDLS respectively associated with the transistors. FIG. 1b shows a diagram of a second bridge arm BI made up of IGBT transistors, ITHS and ITLS, and their associated diodes IDHS and IDLS.
These elementary power switching modules can be combined to form complete switching bridges or combined in parallel to pass the desired current.
Furthermore, it is known to stack circuit subassemblies to produce 3D architectures. Thus, application EP 1,411,551 A1 proposes a power module comprising a central connecting plate, top and bottom electrode plates and electronic switching components that are sandwiched between the central connecting plate and the top and bottom electrode plates. Application DE102014010373A1 teaches an electronic module having first and second printed circuit boards that are superimposed and each include an electronic component. A sintering method is used to connect the boards together.
Today, it appears desirable to propose a new solution suitable for mass production and allowing a better compromise between the different constraints applicable to electric power converters.